Comparison of the quality of hazelnuts unshelled with different sizing and cracking systems

The quality of hazelnuts, sized and cracked by different systems was compared in a commercial processing plant by determining the percentages of nuts that were damaged, broken, left-in the-shell, cracked, unbroken, recyclable, or undamaged. Hazelnuts larger than 16 mm diameter had different cracking behaviour, as compared with smaller ones. In experiments with a traditional Turkish cylindrical sizer and stone cracker combination, 3.3% (standard error 2.7%) damaged nuts were produced when the diameter of the nuts were larger than 16 mm, and 15.9% (7.5%) damaged nuts were produced when the diameter of the nuts was less than 16 mm. The average of the damaged nuts was around 16% with all the conical cracker combinations. Hidden-damage (apparently good appearance from the outside, but darker colour and oily appearance inside) was 38% (4.0%) for the cylindrical sizer/stone cracker combinations, and 41.7% (5.8%) for the cylinder sizer and conical cracker equipped with a big head template combination. Quality control charts (p-charts) for damaged and recyclable nuts were constructed for the hazelnuts from the stone cracker for two diameter ranges. (C) 1997 Silsoe Research Institute.